Tag: inselbergs

Last night we watched the sun set on Uluru. This morning we watched the sun rise on it. It is beautiful at either time. Uluru is a very large inselberg, a rock island, made of coarse-grained sandstone that was weathered from Musgrave, Mann and Petermann mountain ranges to the south and west, deposited by a river system in an alluvial fan. Think of a river delta, where sands and gravels are washed down from eroding mountain ranges and deposited in flat or rippled sheets. (A guide who had been certified by the national park explained that the sand had been deposited in 100,000 year layers in a deep pit and then baked together by heat from the earth’s core like a cake. Misleading ‘science’ like this is more common than one would hope.)

Uluru at Sunrise

About 50% of the sandstone grains are feldspar, 25-35% are quartz
and the rest are grains of rock fragments including basalt. Because of the high
iron content, the exposed face of the sandstone is mainly red, but the hue
changes from deep maroon to glowing ochre depending on the time of day and the brightness
of the sunlight. The sunset and sunrise watch-parties celebrate the color
changes, which are easy to see because Uluru is set in a plain with only
vegetation to disrupt the sign line.

Inselbergs are by their nature unusual, grand features of the landscape that attract everyone’s attention, so it is not a surprise that European explorers found them as compelling as the Originals. The rock became a sacred site for both visiting and local Original groups, a meeting place, a place to gather to hold ceremonies. Among the marks left by Originals, there are many petroglyphs, some of which we were allowed to see and photograph. (There are restrictions on what and where you can take photos at Uluru. These are imposed by the Originals tribe that now owns the rock.) Marks left by the Europeans include the steel chains and posts drilled into the rock where people used to climb it, and artifacts on the playa, including the airplane runway and former campgrounds.

These are petroglyphs from a cave called Kulpi Mutitjulu near a waterhole – a pond at the base of one of the ravines that run down the rock. The petroglyphs range in age from the 1930s back to early times. Research on the age is not permitted. The symbol of concentric circles represents waterholes.

The waterhole is nearly dry at this time, but can fill up quickly when the water is channeled down the rock. The central dark colored triagle is water. Keeping the waterhole clean of debris such as branches and dead animals was the work of the women, in a culture where roles were very strictly divided between men and women. Many of the stories we were told involved the distinction between men’s and women’s spheres of work and influence.